Ultraviolet radiation can be damaging to skin. Immediate damage may be in the form of erythma. More long term is the concern of carcinomas or even melanoma. For these reasons, photoprotective agents, known as sunscreens, have been incorporated into cosmetic compositions.
It is known, generally, that the sun's UVA radiation has wavelengths between 320 and 400 nm. Such UVA radiation can burn the skin and overexposure has been linked to skin cancer. The sun's UVB radiation has a wavelength between 280 and 320 nm and has also been linked to short and long-term skin damage including deep wrinkle formation, collagen breakdown and mottled pigmentation. Protection from the sun's UVA and UVB rays is, therefore, desired.
Dibenzoylmethane derivatives are known sunscreens capable of absorbing UVA rays. While often used, these sunscreens are relatively sensitive to UV rays and tend to decompose upon exposure to sunlight. Moreover, dibenzoylmethane derivatives, which are essentially ineffective as a UVB radiation protector, are often formulated with UVB radiation sunscreens like p-methoxycinnamic acid. Unfortunately, UVB radiation sunscreens tend to accelerate the photodecomposition of dibenzoylmethane derivatives. Thus, compositions with both dibenzoylmethane derivatives and p-methoxycinnamic acid need to be applied frequently by consumers in order to ensure adequate protection from the sun's rays.
There is a need to generate topical sunscreen compositions that provide both UVA and UVB protection and that do not rapidly lose their benefit in the presence of sunlight. Moreover, there is a need to generate topical sunscreen compositions where the UVA and/or UVB sunscreens do not interfere with additional ingredients in the compositions, including each other.
This invention, therefore, is directed to sunscreen composite particles and compositions comprising the same. The particles comprise a traditional UVA sunscreen, are unexpectedly suitable to provide both improved UVA protection, and UVB protection and are substantially free of supplied UVB sunscreen. Such particles may be used to formulate compositions that do not display rapid degradation of UVA sunscreen.
Additional Information
Efforts have been disclosed for making sunscreen compositions. In U.S. Pat. No. 4,387,089, light-screen compositions with 4-(1,1-dimethylethyl) 4′-methoxydibenzoylmethane are described.
Other efforts have been disclosed for making sunscreen compositions. In U.S. Pat. No. 6,306,373, a specific eutectic mixture using lower alkyl phthalimide in a sunscreen composition is described.
Still other efforts have been disclosed for making sunscreen compositions. In U.S. Patent Application Publication No. 2009/0324659, sunscreen composite particles for use in compositions are described.
None of the additional information above describes a sunscreen composite particle suitable for use in a composition displaying both UVA and UVB protection as claimed in this invention.